The background description provided herein is for the purpose of generally presenting the context of the present invention. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present invention.
In the case of disturbance, motor rotors in a power system may relatively swing to cause sustained oscillations in the absence of damping, with an oscillation frequency in a range of about 0.1-2.5 Hz, which is thus called low-frequency oscillations. The low-frequency oscillation problem falls into a category of small disturbance stability. Along with expansion of the scale of interconnected power systems, operation of long-distance heavy-load transmission systems and applications of rapid automatic excitation regulators and rapid excitation systems, the low-frequency oscillation problem occurs in many power systems at domestic and abroad. Low-frequency oscillations are one of the important factors that affect safe and stable operation of the power systems.
Forced power oscillations are one type of the low-frequency oscillations, that is, when a frequency of a system suffered from external sustained periodic power disturbance is close to the natural frequency of power oscillations of the system, significant power oscillations occur. Tang Yong, in Fundamental Theory of Forced Power Oscillation in Power System published in POWER SYSTEM TECHNOLOGY 2006, 30 (10): 29-33, Yang Dongjun et al., in Mechanism Analysis of Low-Frequency Oscillation Based on WAMS Measured Data published in AUTOMATION OF ELECTRIC POWER SYSTEMS 2009, 33 (23): 24-28, and Yang Dongjun et al., in Analysis of Forced Power Oscillation of Power Systems caused by Asynchronous Connection of Synchronous Generators published in AUTOMATION OF ELECTRIC POWER SYSTEMS 2011, 35 (10): 99-103, through theories and analysis on practical cases of power grids, demonstrate that the most effective measure for the forced power oscillations is to quickly find and cut-off the disturbance source. However, they do not present a specific method of finding the disturbance sources.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.